Chris Albertson
>To: Bob Stewart ; Discussion of precise time and frequency
>measurement
>Sent: Wednesday, March 26, 2014 11:25 AM
>Subject: Re: [time-nuts] RC TIC linearity correction?
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>Yes a lookup table would be easy. But how to create the table? I've bee
Hi
Having done this - it gets really boring to sit there for 10,000 seconds and
collect data. Best to automate the process.
In reality you want to run three groups of 10,000 samples and see how they
relate to each other. With some approaches you can find some disturbing things
going on.
Bob
A random source will need a lot more samples in each bucket to reduce
the noise to an acceptable level.
To determine the relative bucket width with a 10% error requires at
least 100 samples per bucket.
For 1% error at least 10,000 samples per bucket.
All thats really required is a sufficiently
t
>Sent: Wednesday, March 26, 2014 11:25 AM
>Subject: Re: [time-nuts] RC TIC linearity correction?
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>On Wed, Mar 26, 2014 at 8:41 AM, Bob Stewart wrote:
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>Thanks Charles. That makes sense, but at the expense of adding unwanted
>complex
On Wed, Mar 26, 2014 at 8:41 AM, Bob Stewart wrote:
> Thanks Charles. That makes sense, but at the expense of adding unwanted
> complexity. As I've been moving the setpoint around this morning, I think
> I see a way to characterize what it's doing. Maybe I can come up with a
> small correction
I hadn't given any thought to correcting the linearity of the TIC I
built, but my PLL plots tell me I should do it now.
One method would be to calibrate with a series of buckets that you fill by
sampling a random source, the more samples in a bucket the more range in
phase for that bucket.
purposes.
Bob
>
> From: Charles Steinmetz
>To: Discussion of precise time and frequency measurement
>Sent: Wednesday, March 26, 2014 12:27 AM
>Subject: Re: [time-nuts] RC TIC linearity correction?
>
>
>Bob wrote:
>
>>I hadn
Bob wrote:
I hadn't given any thought to correcting the linearity of the TIC I
built, but my PLL plots tell me I should do it now.
You are using a resistor to charge the integrating capacitance, so it
charges with the classic exponential curve and you get a nonlinear
time-to-voltage conversi
I hadn't given any thought to correcting the linearity of the TIC I built, but
my PLL plots tell me I should do it now. Explanation: when I arrange things so
that the phase point is near the top of my TIC's range, it requires a smaller
movement than when the phase point is in the middle: Presu
